Medical support devices are known in the art. An artery support device is also called a stent. Methods for manufacturing stents are known in the art. U.S. Pat. No. 5,767,480, to Anglin et al., is directed to a hole generation and lead forming for integrated circuit lead frames using laser machining.
U.S. Pat. No. 5,073,694 to Tessier et al., is directed to a method and apparatus for laser cutting a hollow metal work-piece. The method provides for the cutting of the hollow metal work-piece while minimizing or eliminating residue adherence to the inner circumference of the work-piece. Coolant is pumped through the apparatus to contact the inner portion of the work-piece before and during laser cutting.
U.S. Pat. No. 5,345,057 to Muller, is directed to a method of cutting an aperture in a device by-means of a laser beam.
U.S. Pat. No. 5,780,807 to Saunders, is directed to a method and apparatus for direct laser cutting of metal stents. The expandable stent is made from a single length of tubing and utilizes direct laser cutting from a single metal tube using a finely focused laser beam. The stent may be made in a variety of ways, but the preferred method provides for cutting a thin-walled tubular member of materials such as stainless steel in order to remove portions of the tubing and give a desired pattern. This is done by utilizing a laser beam.
U.S. Pat. No. 5,707,385 to Williams, is directed to a drug loaded elastic membrane comprising an expandable sheath for delivering a therapeutic drug in a body lumen. The expandable membrane has a first layer and a second layer, which are joined along their edges to form a fluid-tight seal. Before joining the layers, a plurality of apertures are formed in the first layer by known methods such as using a laser.
U.S. Pat. No. 5,843,117 to Alt et al., is directed to an implantable vascular and endoluminal stent and the process of fabricating the same. Tube-type stent is fabricated from tubing with longitudinally oriented struts coupled together by bars or bridges, which define a plurality of through-holes in the wall of the tube. This multiplicity of through-holes is cut by a laser beam.
U.S. Pat. No. 5,531,741 to Barbacci, is directed to illuminated stents which are designed as an improved light emitting device. The stent is formed by extruding a length of tubing and then followed by molding and shaping. Drainage openings are formed in one step of the process. These holes may be made by piercing the wall of the tubing by utilizing a sharpened cutter or by use of a laser.
Electromagnetic forming (EMF) is known in the art. In general, this method is used to form, cut, pierce, and join metals having relatively high electrical conductivity, such as copper, mild alloy, aluminum, low-carbon steel, brass, and molybdenum. The EMF process uses a capacitor bank, a forming coil, a field shaper (mandrel), and an electrically conductive work-piece to create intense magnetic fields that are used to do useful work. This intense magnetic field, produced by the discharge of a bank of capacitors into a forming coil, lasts only a few microseconds. The resulting eddy currents that are induced in a conductive work-piece that is placed close to the coil, then interact with the magnetic field to cause mutual repulsion between the work-piece and the forming coil. The force of this repulsion is sufficient to stress the work metal beyond its yield strength, resulting in a permanent deformation. The magnetic field rapidly accelerates the work-piece against the mandrel, thus forming it to the desired shape. Because the actual forming takes place in a matter of a few microseconds, the high strain rate forming does not affect the material properties in an adverse way. The pressure induced on the work-piece, is comparable to that encountered in mechanical forming of similar parts.
EMF can be usually applied to five forming methods: compression, expansion, contour forming, punching and joining. It is used to expand, compress, or form tubular shapes, to form a flat sheet, and to combine several forming and assembly operations into a single step. It is used in single-step assembly of metal parts to each other or to other components, such as in electrical cables, and joining of aluminum and copper. Highly resistant metals such as titanium, need special EMF equipment, which operate at higher frequencies in the range of 20 to 100 kHz.
Because the material is loaded into its plastic region, the springback often associated with mechanical forming, is virtually absent in electroformed parts. Joints made by EMF process are typically stronger than the parent material, and compared to other joining methods, such as laser welding. Assemblies using metal parts formed onto plastics, composites, rubber, and ceramics are also common.
More information regarding EMF can be found in the following references: V. S. Balanethiram, Xiaoyu Hu, Marina Altynova and Glenn S. Daehn, “High Velocity forming: Is it Time to Rediscover This Technology”, Engineering Research Center Report ERC/NSM-S-94-15, The Ohio State University, Columbus, Ohio, 1994, PP. 36-37, V. S. Balanethiram, Xiaoyu Hu, Marina Altynova and Glenn S. Daehn, “Hyperplasticity: Enhanced Formability at High Rates”, Journal of Materials Processing Technology, Vol. 45, 1994, pp. 595-600, G. S. Daehn, M. Altynova, V. S. Balanethiram, G. Fenton, M. Padmanabhan, A. Tamhane, and E. Winnard, “High-Velocity Metal Forming—An Old Technology Addresses New Problems”, JOM, Vol. 7, July 1995, pp. 42-45, and Metals Handbook, 9th Edition, Volume 14, Forming & Forging, ASM Electromagnetic Forming International, Metals Park, Ohio, pp. 644-653.
U.S. Pat. No. 6,153,252 issued to Hossainy et al., and entitled “Process for Coating Stents” is directed to a method for coating stents in order to prevent the formation of bridges. The stent is placed over a mandrel whose outer diameter is less than the inner diameter of the stent. The stent and the mandrel are dipped into the coating solution. The stent and the mandrel are removed from the coating solution and the coated stent is moved relative to the mandrel. The relative outer diameter of the mandrel and the inner diameter of the stent is such that while the coating is still wet, the movement of the stent along the length of the mandrel, clears the passages of the stent, which remain open after drying.
U.S. Pat. No. 5,534,287 issued to Lukic and entitled “Methods for Applying an Elastic Coating Layer on Stents”, is directed to methods for applying a covering layer to an expandable stent, the expandable stent having a discontinuous wall. The covering layer is an elastomeric polymerizable composition. The expandable stent which is in form of a wire mesh, is radially contracted. The inner surface of a tube is coated with a lifting medium, in order to prevent adherence to the covering layer. The expandable stent is inserted into the tube and the expandable stent is allowed to radially expand.
The assembly of the tube and the expandable stent is wetted in the elastomeric polymerizable composition, dissolved in a sufficient amount of solvent, to permit wet forming of a continuous covering layer around the expandable stent. The solvent is evaporated, the elastomeric polymerizable composition is polymerized in the tube and the stent which is covered with the covering layer, is removed from the tube.